The present invention pertains to the field of optical switching and fiber optics. The present invention relates to optical switching devices and fiber optic components. More particularly, the present invention relates to high uniformity lens arrays having lens correction and methods for fabricating the same.
An optical switching device couples light beams from an input fiber to an output fiber. In many optical switching systems, the light beams represent data in digital form. Typically, light beams form an input fiber are collimated and directed toward a desired location such as an output fiber. Lens arrays are used to collimate and direct beams of light to a desired location for optical switching devices. For example, lens arrays may be used to focus collimated beams of light to a mirror device, which redirects the beams of light.
FIG. 1 depicts an illustration 100 of a prior art lens array 104 outputting collimated light beams 108. Lens array 104 receives light beams outputted form fiber input block 102 through fibers 106. Light beams from fibers 106 are directed to corresponding lenses 104A of lens array 104. Lenses 104A collimate the beams of light. Lenses 104A may also focus the beams of light to a location based on the curvature and position of lenses 104A for lens array 104. Furthermore, the position of fibers 106 with respect to lenses 104A also affect the manner in which lenses 104A collimate and focus light beams.
A problem associated with prior art lens array 104 is uniformity. That is, if lenses 104A are not formed uniformly for lens array 104, collimated light beams 108 may not be collimated or focused correctly. For example, a small error in position of lenses 104A on the order of 1 xcexcm may cause significant focal angle or position error for a light beam. As shown in FIG. 1, if one of the lenses for lens array 104 is positioned incorrectly relative to the corresponding input fiber, light beams will enter the lens off center and, thusly, be directed at an improper angle and location that may cause data loss in some switching systems.
Furthermore, a small error in the shape or curvature lenses 104A for lens array 104 may affect the focal distance for light beams passing through the lens. As a result, the light beams may not be collimated and may converge or diverge thereby causing undesirable results. For a large optical switch, the distances that light beams must travel become large and thus the parameters for focal position and focal distance become tight.
Uniformity is also necessary for the position and curvature of the lens array 104 with respect to the fibers 106 when the collimated light beams 108 of FIG. 1 are incident on the lens array 104 and focused onto an output fiber. That is, an error in relative position of a lens and an input fiber may cause the light beam passing through the lens to be focused off center, which reduces coupling of optical power into an output fiber and increases loss. Furthermore, an error in curvature of the lens causes light to be focused in front or past the end of a fiber, which also reduces coupling of optical power into the fiber and increases loss.
Typically, for such error in the prior art lens array, the error tolerance is either accepted or the error is corrected by remaking the lens array with precise control of the lens fabrication. Thus, a disadvantage in the prior art is that error tolerances may not be acceptable for ultra-low-loss optical switches. Furthermore, to fix the error of a single lens for a lens array by remaking the lens array is inefficient.
A lens array having corrective measures is disclosed. The lens array includes a substrate. A plurality of primary lenses are formed from the substrate. A corrective measure is formed for each primary lens having a uniformity error such that the corrective measure corrects the uniformity error.
A method of fabricating a lens array is disclosed. A plurality of primary lenses are formed from a first side of a substrate. A uniformity of the plurality of primary lenses are measured. A corrective measure is formed for each primary lens having a uniformity error based on the measured uniformity such that the corrective measure corrects the uniformity error.
Other features and advantages of the present invention will be apparent from the accompanying drawings, and from the detailed description, which follows below.